The Relationship between the Cell Electrical Potential Difference and Salt Uptake in the Roots ofHelianthus annuus

The effect of ringing the stem on the electrical potential difference (PD) in the root cortical cells of H. annuus was studied. PD and salt transport were followed simultaneously. By ringing it was possible to separate the PD from K⁺, $NO3-$⁠, and Cl⁻ uptake and H⁺ efflux. The uptake of phosphate however was found to be closely connected with a component of the PD. It was concluded that there is an electrogenic pump for phosphate in these roots which generates 60–80 mV.